Project Summary The majority of the human population is latently infected by herpes simplex virus type-1 (HSV-1), yet there are no effective therapies for clearing latent virus. During latency, the virus curbs lytic gene expression and only express a select few noncoding RNAs, including the latency associated transcript (LAT) and viral miRNAs. The biological functions of most HSV-1 miRNAs, in the context of viral infection, are largely unknown. Putative targets for HSV-1 miRNAs H1, H6, and H8 include viral and host transcripts. However, evidence for these mechanisms rely primarily on transient expression assays. Rigorous phenotypic analyses of recombinant viruses lacking individual miRNAs in cells relevant to HSV-1 biology and in vivo, in the context of viral infection, will elucidate the biological significance of these viral miRNA interactions in HSV-1 pathogenesis. Hypothesis: HSV-1 miRNAs H1, H6, & H8 will be found to facilitate HSV-1 lytic, latent, and/or recrudescent infections by fine-tuning the translation of viral and host transcripts. Since miRNAs repress translation, a virus lacking a miRNA that targets 1) a lytic gene, will increase virulence or 2) the host immune response, will decrease virulence. In addition, I may find that these miRNAs have multiple host or viral targets, that work synergistically or antagonistically to regulate the dynamic state of viral latency. Aim 1: Phenotypic & mechanistic analyses of miR-H1, H6, and H8 during acute infection in cell culture. Aim 2: Determine the effects of miR-H1, H6, and H8 on pathogenesis during acute infection in the mouse footpad infection model. Aim 3: Characterize the roles of miR-H1, H6, and H8 in latency and reactivation in murine dorsal root ganglia.